why is it so difficult to start a meditation practice?

One reason is the concept people have of meditation.
They know of meditation from what they see in movies and on TV, where someone is just sitting and meditating for a long time, and then becomes enlightened.

This is not real life, and that is not how meditation works.

For a meditation practice to be effective, and consistent, you need to understand what to expect.
When you first start out, you won't be enlightened, it may even be a little bit painful since people are usually not used to sitting in a position like you do when you meditate, and especially not for longer periods of time. On top of that, you may just feel a general discomfort, boredom, and may see yourself full of more thoughts than you had before you started meditating.

All of these things are normal, and that is the reality of beginning meditating. It's not easy, it's a practice that takes time to get good at.

How does this all help?
Now that you know what to expect, you can understand that first, you will not be enlightened after one or two meditation sessions. Second, that it won't just magically clear your mind of thoughts. And third, that yes, it is uncomfortable, but this gets better quickly.
With all that said and understood, you can now focus on the practice itself rather than what you will theoretically get out of it.

Focus on the practice and on making it consistent. Try to meditate every day for just a few minutes a day, even 5 minutes. If you can't do it every day, then every other day, or as often as you can.
Once you do this consistently, you will slowly realize and feel that you can meditate for longer periods of time, and more frequently. After some time, you will begin to realize the effects of this practice.
But if you jump in to the practice already expecting to see all the results and benefits after just a few sessions, and to be able to sit and meditate for 30 minutes or longer, then you will probably be joining the people who tried out meditation and say that it doesn't work.